It is a general goal of pump design to reduce the overall power consumption of a pump as much as possible. Speed controlled wet rotor pumps usually comprise a frequency converter configured to drive the motor at a desired speed according to the required pumping power. In order to drive the motor with a pulse width modulated signal having a sinusoidal shape, the switching frequency of the frequency converter must be high, which introduces switching losses in the frequency converter.
EP 2 133 991 describes a speed controlled pump in which the input voltage to the frequency converter is adapted by a voltage converter to the required output voltage aiming for a maximum modulation index for minimizing switching losses in the frequency converter.